Flow regulation



Oct. 9, 1928.

I N VEN TOR. yam Q )MM W1 A TTORNEYS.

Y B K v A m: l mu J I m. .F J W E Patented Oct. 9,

PATENT OFFICE.

UNITE!) STATES JAMES A. HEDGCOGK, OF DAYTON, OHIO, ASSIGNOR TO THEMANAGEMENT ENGI- NEERING AND DEVELOPMENT COMPANY, OF DAYTON, OHIO, f1CORPORATION OF OHIO.

FLOW REGULATION.

Application filed January 29, 1927. Serial No. 164,448.

In the manufacture of paper from fibrous materials, it is the generalpractice to suspend the fibrous material in water to produce a pulp orpaper stock, the relative proportions 6 of fibrous material to waterbeing controlled to give a consistency which is such that the pulp orpaper stock may be pumped or flowed through pipes or troughs to the stuif or stock chests, the head boxes, or the like. Herein- 10 after suchsuspensions of fibrous material in water will, for purposes ofdescription, be referred to as fibrous stock, and this term is intendedto include the various forms of fibrous suspensions, used in papermaking.

In general, there is a consistency of fibrous stock which is mostdesirable for given operating conditions and desired results. and thisconsistency having been determined it IS desirable that there be nomaterial variations therefrom. The consistency may be roughly controlledby taking samples from time to time and varying the consistency ordilution from time to time; but it is desired to secure continuouscontrol.

Heretofore quite satisfactory means has been provided for controllingthe consistency of such stocks as are known as thick stock. by which ismeant fibrous stock containing from 3% of dry fiber upwards. But therehas been no method or apparatus for successfully controlling orindicating with respect to fibrous stocks of'lower consistency, so thatcontrol might be effected, of the consistency of the stock when thepercentage of fibrous material is materially below 3%. Especially isthis so in the case of thin stock in which the consistency is in theneighborhood of 1% or less.

One of the principal objects of this invention is to provide a method ofcontrolling the consistency of fibrous stock, which method is applicablealso to thin stock, and is more accurate than methods heretofore used.

Another object of this invention is to provide apparatus for carryingout the above method.

Other objects and advantages of this invention will be apparent from thefollowing description when taken in connection with the accompanyingdrawing.

In the drawing in which like characters of reference designate likeparts throughout the several views thereof;

Fig. 1 is an isometric view of apparatus for practising the invention;and

Fig. 2 is an elevational view of a modified form of resistance elementadapted for use with the apparatus of Fig. 1.

It has been heretofore attempted to effect control of the consistency offibrous stocks on the basis of variations in flow through an orificeaccompanying variations in the proportionate quantity of fibrousmaterial in sus-' tions may be magnified into a satisfactorily 1 workingmagnitude by flowing the thin stock through a suitable flow passagesuchfor example as a pipe of moderate diameter, and in-,

terposing a resistance to the flow of the stock through the pipe. n

I have discovered that when a pressure head is impressed upon thefibrous stock passing through such a flow pipe or passage. with suitableresistance to flow, the residual head existing at a predetermined pointalong said flow passage is proportional to-the consistency of the stock.Furthermore. it has been discovered that this residual head varies quitemarkedly for small changes in the consistency of the stock, thisvariation. in residual head being sufficient for an accurate control ofthe consistency of the stock by means of pressure actuated mechanism. InView of the fact that small differences in stock consistency produceappreciable differences in residual head, a thin stock can be readilycontrolled; in fact, a stock having a consistency considerably less than1% lends itself readily to this control.

Referring to the drawing, in which there is illustrated a preferredembodiment of apparatus designed for carrying out the method of thisinvention, there is disclosed in Fig. 1 a conventional pulp stock trough10 through which a continuous stream of fibrous stock,

with a 4-inch diameter of the coils.

from any suitable source (not shown), is

- adapted to flow to subsequent treating apparatus (not shown).

The stock received at the inlet end of the trough may have any suitablepracticable consistency range, roughly controlled within reasonablelimits with respect to the actual definite consistency desired,thisbeing usual paper mill practice, and means for effecting this roughcontrol being therefore notshown. Associated with the trough is adilution pipe 14 which is arranged to discharge additional dilutionwater into thestock passing through the trough. The amount of additionaldilution water added to the stock from the pipe 14 is controlled, inaccordance with the consistency of the resulting diluted stock to maintain such diluted consistency as desired.

Preferably this control apparatus is constructed to operate upon only aportion of the stock passing through the trough 10, a small portion ofthis stock being withdrawn from the main portion thereof for thispurpose. A centrifugal pump 20 has its suction side connected by a pipe21 to the passage within the trough 10, beyond the point of discharge ofpipe 14.

The pipe 21 extends within the trough 10 transversely thereof and isprovided with a plurality of perforations 22 whereby a representativeportion of the stock passing through the trough is obtained. The pump 20is driven by a constant speed motor 23, of any suitable conventionaltype. The outlet of the pump is connected to a flow pipe 30, ofconsiderable length, and is preferably of comparatively small diameter.A coil 31, which gives added resistance to the flow of the stock, isinserted within the pipe 30. In actual practice satisfactory resultshave been secured with 10 feet of %-inch pipe coiled With suchapparatus, the residual head is found to be proportional to theconsistency of the stock passing through the flow passage. \Vhen theconsistency of the stock varies it is found that the residual headlikewise varies quite markedly, and the use of the long flow assa e,especially with a tortuous coil or the like t erein, multiplies thisvariation in resistance,-and correspondingly varies the residual head. Aresistance element such as that shown in Fig. 2, comprising a pipe 35bent to form a plurality of reverse bends, may be used in place of thecoil if desired. The constructionof the resistance element in any caseis suchthat a substantial portion of the pressure head of the flowingstock is converted into lost friction head. The result is that at anypredetermined point along the line of How there exists a residualpressure, which residual pressure varies with the con sistency of thestock.

This variation in residual head is utilized according to this inventionto control the rate of addition of dilution water added through the pipe14 to the stock. For this purpose, a suitable pressure element 40 ispositioned to be responsive to this'residual head. Satisfactory resultsare obtained-by connecting this'pressure element to the flow passage ata point beyond the resistance element 31. The pressure element 40 isshown as a bellows or sylphon 41, the interior of which is connected tothe flow passage and is therefore responsive to the residual headexisting therein at the point of connection.

This pressure element is designed to actuate a suitable valve indicatedgenerally at 45 positioned within the dilution ipe 14 to control theflow therethrough. is shown, the valve is a balanced valve provided witha stem 46 cooperatively connected to one arm 47 of an actuating leverpivoted at- 48, the other arm 49 of which is pivotally connected at 50to an extension 51 of the sylphon 41. A spring 55 is provided to effectclosing movement of the valve.

In order to vary the consistency of the thin stock being controlled, asliding weight 60 is provided on one arm of the lever, a number ofnotches 61 being formed in the lever to accurately position the weight60. Thus the consistency of the stock may be controlled over a widerange, and for any one setting of the weight 60 the consistency ismaintained substantially constant.

Infoperation, stock of generally controlled consistency is flowedthrough the trough 10 and.is diluted to the desired consistency withadditional water introduced through pipe 14. A continuous portion of thediluted stock is withdrawn by the pump 20, which operates to force thestock under controlled head into and through the flow passage andresistance element 31, this resulting in a residual head being eflectiveat the pressure element 40.

Ordinarily the desired controlled head may be obtained by using acentrifugal pump and operating it at a substantially constant speedwithin its normal operating range. As long as the consistency of thestock remains substantially constant, this residual head likewiseremains constant. If the consistency of the stock should vary, theresidual head effective at the pressure element 40 also is varied,causing a movement of the pressure element, thereby rocking the leverarm to further operate the valve 45 in the. dilution pipe 14 to adjustthe supply of dilution water, to bring the stock to the desiredpredetermined consistency. The effect is that fluctuation in the stockconsistency results in the actuation of the control apparatus to controlthe positioning of the valve 45 whereby the consistency of the stock ismaintained substantially constant.

The withdrawn portion of the stock passed through the control apparatusis returned to the trough. A pressure-indicating gauge 01' a suitablepressure-recording instrument may be connected 1n the pipe 30, asillustrated at 65, if desired to indicate or record the consistency.lVhile mechanical connections for actuating the valve 45 have beenillustrated herein, it is to be understood that the pressure element 40can be constructed to operate suitable electrical or other mechanism foractuating this valve.

While the method herein described, and the forms of apparatus forcarrying this method and that changes may be made therein with outdeparting from the scope of the invention which is defined in theappended claims.

\Vhat is claimed is:

1. In the preparation of fibrous stock of thin consistency, the methodwhich comprises diluting said stock to a predetermiiied consistencyrange, adding an additional supply of dilution water to said stock,impressing a predetermined head upon said additionally diluted stockwithin a flow passage, and controlling the supply of additional dilutionwater in accordance with the residual head at a predetermined point insaid flow passage.

2. In the preparation of fibrous stock of thin consistency, the methodwhich comprises diluting said stock to a predetermined range of thinconsistency, varying the relative proportion of dilution water in thestock to secure a predetermined substantially constant consistency byintroducing controlled quantities of additional dilution water, andcontrolling the quantity of such additional dilu- I tion water byimpressing a controlled head upon the resulting additionally dilutedstock while said resulting stock is passing through a flow passage, inaccordance with the resid ual head at a predetermined point in said flowpassage.

3. In the preparation of fibrous stocks of thin consistency, the methodwhich comprises diluting said stock to a predetermined consistencyrange, adding additional controlled quantities ofdilution water to saidprevious,

ly diluted stock, withdrawing a portion of the resulting diluted stock,impressing a predetermined head upon said withdrawn portion ofadditionally diluted stock within a flow passage. and controlling thesupply of additional dilution water in accordance with the residual headat a predetern'iined point in said flow passage.

4. Apparatus of the character described, comprising means for causing acontinuous flow of fibrous stock or the like, a dilution pipe for addingdiluting liquid to said flowing stream of stock, a valve within saidpipe for controlling the flow therethrough, means beyond said dilutionpipe for withdrawing a portion of said diluted stock from the flowingstream, and control means responsive to the consistency of the withdrawnportion of said diluted stock for controlling the positioning of saidvalve, said control means including a flow passage, means for impressinga controlled head upon'said withdrawn por tion of stock within said flowpassage, and pressure-actuated means responsive to the residual head ata predetermined point in said flow passage.

5. Apparatus of the character described, comprising means for causing acontinuous flow of fibrous stock or the like, a dilution pipe for addingdiluting liquid to said flowing stream of stock, a valve within saidpipe for controlling the flow therethrough, means beyond said dilutionpipe for withdrawing a portion of said diluted stock from the flowingstream, and control means responsive to the consistency of the withdrawnportion of said diluted stock for automatically controlling thepositioning of said valve to thereby maintain the consistency of saidflowing stream of diluted stock substantially constant, said controlmeans including a power driven pump having its suction side connectedwith said diluted stock withdrawal means, a flow passage connected tothe pressure side of said pump, and pressure-actuated means responsiveto the residual head at a prede: termined point in said flow passage.

6. Apparatus of the character described, comprising means for causing acontinuous flow of fibrous stock or the like, a dilution pipe for addingdiluting liquid to said flowing stream of stock, avalve within said pipefor controllingthe flow therethrough, means beyond said dilution pipefor withdrawing a portion of said diluted stock from the flowing streamand control means responsive to the consistency of the Withdrawn portionof said diluted stock for automatically controlling the positioning ofsaid valve to thereby means, a flow passage of substantial resistance tofluid flow connected to the pressure side of said pump, andpressure-actuated means responsive to the residual head at apredetermined point in said flow passage.

7. Apparatus of the character described, comprising means for causing acontinuous flow of fibrous stock or the like, a dilution pipe for addingdiluting liquid to said flowing stream of stock, a valve within saidpipe for controlling the flow therethrough, means beyond said dilutionpipe for withdrawing a portion of said diluted stock from the flowingstream, and control means responsive to the consistency of the withdrawnPOItIOH of said diluted stock for automatically controlling thepositioning of said valve to thereby maintain the consistency of saidflowing stream of diluted stock substantially constant, said controlmeans including a power driven pump having its suction side connectedwith said diluted stock withdrawal means, a resistance element connectedto the pressure side of said pump, and a pressure element associatedwith said valve and responsive to variations in residual'head existingbeyond said resistance element.

8. In apparatus for controlling the consistency of thin fibrous stock orthe like, a supply of fibrous stock, a pump, said pump having thesuction side thereof connected to I said source of fibrous stock, adischarge pipe on the pressure side of said pump, resistance meansWithin said discharge pipe, and a pressure element connected within saiddischarge pipe beyond said resistance means and responsive to theresidual head existing therein at its point of connection.

9. In apparatus for controlling the consistency of fibrous stock or thelike, a supply of fibrous stock, a centrifugal pump having its suctionside connected to said supply of fibrous stock, a discharge pipeconnected to the delivery side of said pump, means for driving said pumpfor impressing a c0ntrolled head on the stock delivered to saiddischarge pipe, and a pressure element connected within said dischargepipe and constructed to be actuated by variations in residual pressureexisting at its point of connection.

10. Apparatus of the character described, comprising a supply of fibrousstock, a dilution pipe adapted to introduce a dilution liquid into saidfibrous stock, a valve within said pipe, a centrifugal pump having itssuction side connected to said supply of fibrous stock, means fordriving said pump at substantially co stant speed, a discharge pipeconnected to tli'edelivery side of said pump, a pressure elementconnected within said discharge pipe and adapted to be actuated byvariations in residual head therein. and means interconnecting saidvalve and said pressure element whereby said valve is automaticallypositioned in accordance with the residual head effective on saidpressure element.

11. In the preparation of fibrous stock of controlled consistency, themethod which comprises impressing a predetermined head upon fibrousstock within a flow passage, and

= controlling the supply of dilution liquid to the fibrous stock inaccordance with the residual head effective at a predetermined point inthe fioW passage.

12. In the preparation of fibrous stock of controlled consistency, themethod which comprises impressing a predetermined pressure head uponfibrous stock'within a flow passage, consuming a substantial portion ofsaid head in resistance loss by flow through the passage, andcontrolling the supply of dilution liquid to the fibrous stock inaccordance with the residual head effective at a predetermined point insaid flow passag after loss of the resistance head.

13. In apparatus of the character described-for controlling. theconsistency of fibrous stock, a flow passage to which fibrous stock issupplied, means forimpressing a predetermined head upon the stock withinsaid passage, a dilution liquid supply means for the fibrous stock, andmeans responsive to the residual head effective at a predetermined pointin said flow passage for controlling said dilution liquid supply means.

14. In apparatus of the character described for controlling theconsistency of fibrous stock, a flow passage, means for causing a fiowof fibrous stock through said flow passage, said flow passage having ahigh resistance to flow therethr'ough to produce a substantialresistance loss upon fiow of thin fibrous stock of less than 3%consistency through said passage, dilution means for said stock, andmeans responsive to the consistency of the stock passed through saidflow passage for controlling said dilution means to maintain theconsistency of the stock substantially constant.

15. In apparatus of the character described for controlling theconsistency of fibrous stock, a flow passage, means for causing a flowof fibrous stock at high velocity through said flow passage, thevelocity of the stock being coordinated with the resistance to flowthroughthe passage to produce a substantial friction loss upon flow ofthin fibrous stock of less than 3% consistency through said passage,dilution means for said stock, and means responsive to the consistencyof the stock passed through said flow passage for controlling saiddilution means to maintain the consistency of the stock substantiallyconstant. i i

In testimony whereof I hereto aifix'my signature.

JAMES A. I-IEDGOOCK.

no I

